Water-retaining artificial turf

ABSTRACT

The invention relates to artificial turf, synthetic backing material, synthetic filament, and cooling of artificial turf. The artificial turf comprises synthetic turf filaments, the synthetic turf filaments comprise a blend, the blend comprises 65-99.5% by total weight of the blend of a polyolefin, and 0.5-35% by total weight of the blend of a hydrophilic polymer, wherein the polyolefin is polyethylene, polypropylene, or any combination thereof, and wherein the artificial turf is preferably in the form of a tile carpet.

The invention relates to artificial turf, synthetic backing material, synthetic filament, and cooling of artificial turf. Artificial turf (also commonly known as, e.g., synthetic turf, artificial grass, and synthetic grass, or simply, turf) has been used prominently in sports fields and landscaping as an alternative to (natural) grass. In more recent years, as properties of artificial turf have improved, it has also become a popular choice for pets, for use in playgrounds, gardens, and in other leisure and commercial applications.

Despite that artificial turf offers multiple benefits that grass cannot, such as no fertilising required, and improved durability and resilience, a major drawback to artificial turf is heat. Artificial turf can get very hot under certain conditions, especially when sunlight hits its surface. When compared to grass, artificial turf tends to hold more heat, often creating a surface that is too hot to touch, thereby possibly leading to burn wounds. And even in some cases, when the surface of the artificial turf gets too hot, beneficial properties of the turf may get lost.

Typically, artificial turf is protected from overheating by planting trees, bushes, and shrubbery in its vicinity, such that shadows provide relief from hot sunshine and deep roots help keep the ground cooler by holding water. Another possibility is to switch to an infill that is specifically designed to keep artificial turf cool. Also, an evaporative cooling system with which water is circulated around the artificial turf lawn helps lowering the surface temperature.

Various alternative attempts have been made to improve the heat protection of artificial turf.

For example, WO-A-2005/111281 describes a synthetic fibre that reduces the risk of injury to players when used on an artificial grass sports field. The fibre is an extruded core-shell system. CN-B-103 014 898 mentions artificial grass fibres having a hydrophilic surface. The artificial grass fibres comprise a matrix resin, a colour masterbatch, an auxiliary, and a hydrophilic modifier.

WO-A-2008/150156 describes artificial grass composed of fibres comprising a core and a cladding.

EP-A-2 899 301 discloses a method for producing an artificial turf fibre that has hydrophilic properties. The fibre comprises 63 to 88% of polyolefin, 5 to 30% of zeolite, and 7% masterbatch and UV-stabilisers. This composition does not form a blend, but the zeolite filler will be present as solid agglomerates or chunks. Moreover, amongst other the zeolite filler leads to undesirable wear resistance, roughness, resilience, and stiffness.

While these attempts may be useful for some applications, there remains a need for artificial turf having an improved water retention property and preferably improved wear resistance, such that the turf can be kept cool for a longer period of time.

It is an objective of the invention to overcome at least some of the disadvantages faced in the art.

In particular, the invention aims at improving the water retention of artificial turf, especially for artificial turf comprising synthetic turf filaments based on linear low-density polyethylene.

The invention further aims at improving the water retention of artificial turf comprising a synthetic backing, especially wherein the backing is based on polypropylene.

The inventors found that one or more of these objectives can, at least in part, be met by providing the synthetic turf filaments as described herein.

Accordingly, in a first aspect of the invention there is provided artificial turf, comprising synthetic turf filaments, the synthetic turf filaments comprise a blend, the blend comprises 65-99.5% by total weight of the blend of a polyolefin, and 0.5-35% by total weight of the blend of a hydrophilic polymer, wherein the polyolefin is a polyethylene, a polypropylene, or a combination thereof, and wherein the artificial turf is preferably in the form of a tile or carpet.

In a further aspect of the invention, there is provided artificial turf, comprising a synthetic backing, the synthetic backing comprises a blend, the blend comprises 65-99.5% by total weight of the blend of a polypropylene, and 0.5-35% by total weight of the blend of a hydrophilic polymer, preferably a hydrophilic polymer as described herein, and/or in an amount as described herein, wherein the artificial turf is preferably in the form of a tile or carpet.

In a further aspect of the invention, there is provided a synthetic backing material, comprising a blend as described herein.

In yet a further aspect of the invention, there is provided a synthetic filament comprising a blend as described herein.

In yet a further aspect of the invention, there is provided a method of cooling artificial turf, comprising inserting a plurality of a synthetic turf filament as described herein into artificial turf.

The inventors surprisingly found that the blends described herein have advantageous water retention properties.

The term “artificial turf” as used herein is meant to refer to a substrate layer having synthetic turf filaments projecting therefrom, preferably upwardly and/or with different curl intensities, such that it visually resembles natural turf. The substrate layer may be a carpet-like (surface) cover having substantially upright, or upright, synthetic turf filaments, or synthetic turf filaments attached thereto having one or more curl intensities. The synthetic turf filaments may be attached to the substrate layer by mechanically connecting the filaments to the layer, for example, by means of a tufting, weaving, or knitting technique.

The term “blend” as used herein is meant to refer to a physical mixture of two or more different species, wherein at least one species is dispersed in another species which acts as a medium. In particular, the blend as described herein is a polymer blend, i.e. a macroscopically homogeneous mixture of two or more species of polymer. Preferably, the blend is sufficiently stable to form a stable material having unique properties.

The term “filament” as used herein is meant to refer to a yarn, i.e., a strand, such as a twisted strand, of fibre(s), e.g., used for tufting, weaving, or knitting. Filament may refer to the term “fibre” in that a fibre is a single elongated piece of a given material, roughly round in cross-section, and often twisted with other fibres to form thread. Thus, the term filament refers to a thread, thread-like structure, fibre, fibril, and wire-like structure. The filaments as described herein may be in all sorts of sizes and shapes. For example, the filament may be in the form of stem, flat, wave, v-shape, s-shape, c-shape, u-shape, w-shape, or hollow. In particular, the size and shape of the filaments are adapted to their application.

The term “hydrophilic polymer” as used herein is meant to refer to a polymer that comprises polar and/or charged functional groups, rendering the polymer capable to absorb water, e.g., equivalent to multiple of times the polymer's own weight, and possibly even soluble in water.

The term “synthetic turf filament” as used herein is meant to include fibrillated tape yarn, texturised or thatch yarns, coextrude tape yarn, monotape and monofilament yarn. A “fibrillated tape” or “fibrillated tape yarn” is a cast extruded film cut into tape (typically about 1 cm width), the film stretched and long slits cut (fibrillated) into the tape giving the tape the dimensions of grass blades. A “monofilament yarn” is extruded into individual filaments with a desired cross-sectional shape and thickness followed by filament orientation and relaxation in hot ovens. The synthetic turf filament forms the synthetic (polymer) strands for the artificial turf. Artificial turf requires amongst others resilience (spring back), toughness, flexibility, extensibility, and durability. Consequently, synthetic turf filament preferably excludes filaments for fabrics (i.e. woven and/or knit fabrics).

The term “tiles” as used herein is meant to refer to slabs, sods, slices, blocks, derivatives thereof, and alike. The shape of the tiles is not necessarily square or rectangular, but can, for example, also be circular or rhombic.

The artificial turf of the invention comprises synthetic turf filaments. In other words, the artificial turf comprises a plurality of synthetic turf filaments. The filaments comprise a blend, wherein the blend comprises a polyolefin, wherein the polyolefin is a polyethylene, a polypropylene, or a combination thereof. Preferably, the polyolefin comprises or is polyethylene.

The polyethylene may, for example, comprise one or more selected from the group consisting of very low-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Preferably the polyethylene comprises one or more selected from very low-density polyethylene, low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. More preferably, the ethylene comprises linear low-density polyethylene and/or high-density polyethylene. Linear low density polyethylene is preferably used, because the low density gives a product which is very soft to the touch.

The polyethylene that may be present in the blend may have a density, as measured according to ISO 1183, in the range of 0.88-0.99 g/cm³, preferably 0.90-0.96 g/cm³, more preferably 0.91-0.94 g/cm³. The polyethylene present in the blend may have a melt flow index, as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 190° C., of 0.1-10 g/10 min, preferably 0.5-7.5 g/10 min, more preferably 1-5 g/10 min.

The polyethylene present in the blend may have a melting point, as measured according to ISO 11357, in the range of 100-180° C., preferably 105-160° C., more preferably 115-140° C.

The blend may also comprise polypropylene, or a combination of polyethylene and polypropylene. Polypropylenes include homopolymers of propylene, copolymers of propylene and other olefins (including random copolymers and block copolymer), and terpolymers of propylene, ethylene and dienes. Combinations of polyethylene and polypropylene include blends of polypropylene and polyethylene, random copolymers of ethylene and propylene, as well as block copolymers of ethylene and propylene. In the past, polypropylene was considered less suitable for artificial turf than polyethylene, inter alfa, because polypropylene has a comparatively high coefficient of friction, so that when someone slides with their skin along the turf burns can result. However, in accordance with the invention this problem is reduced by the inclusion of a hydrophilic polymer in the blend.

The blend comprises 65-99.5% by total weight of the blend of the polyolefin, wherein the polyolefin is a polyethylene, a polypropylene, or a combination thereof. In particular, the blend may comprise 65-95% by total weight of the blend of polyethylene. The blend may comprise 70% or more, 75% or more, or 80% or more of polyolefin. The blend may comprise 90% or less, or 85% or less of polyolefin. Preferably, the blend comprises 70-85% by total weight of the blend of polyolefin, and more preferably 77.5-82.5%.

The blends as described herein further comprise a hydrophilic polymer. The hydrophilic polymer may comprise one or more synthetic polymers and/or one or more natural polymers. For example, the synthetic polymer may be selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyethylene glycol, polyurethane, N-(2-hydroxypropyl)methacrylamide, xanthane gum, and derivatives thereof. The natural polymer may, for example, be selected from the group consisting of pectines and salts thereof, chitine, chitosan, dextran, cellulose ethers, such as hydroxypropylcellulose, hydroxypropylmethylcellulose and hydroxyethylcellulose, starch, and derivatives thereof. In particular, the hydrophilic polymer comprises one or more hydroxyl groups. Preferably, the hydrophilic polymer comprises polyvinyl alcohol and/or polyvinyl acetate. The hydrophilic polymers surprisingly seem to act as flame retardants, in particular polyvinyl alcohol and polyvinyl acetate. As a result, the use of these polymers allow to reduce the amount of flame retardant additive in the synthetic turf filaments.

The hydrophilic polymer is preferably an extrudable hydrophilic polymer. Preferably, the hydrophilic polymer has a T_(g) of 40° C. or more, such as 50° C. or more, 60° C. or more, 65° C. or more, 70° C. or more, or 80° C. or more. In an embodiment, the hydrophilic polymer has a T_(g) of 50-60° C.

The blends as described herein comprise 0.5-35% by total weight of the blend of hydrophilic polymer. In particular, the blend may comprise 1-30% by total weight of the blend of hydrophilic polymer. For example, the amount of hydrophilic polymer may be 5% or more by total weight of the blend, such as 10% or more, or even 15% or more. The amount of hydrophilic polymer may be 25% or less by total weight of the blend, such as 20% or less, or 15% or less. Preferably the blend comprises 0.5-10% by total weight of the blend of hydrophilic polymer, and more preferably 2-6%.

Advantageously, the blend as described herein may comprise an ionomer resin. An ionomer resin is a polymer composed of electrically neutral repeating units as well as ionised repeating units, which are covalently bonded to the polymer backbone as pendant group moieties. Usually, 5-15 mol % of the repeating groups are ionised repeating units. The ionised repeating units may comprise one or more ionic groups selected from sulphonate, phosphate, phosphonate, and carboxylate ionic groups. Preferably, the ionised repeating units comprise carboxylate ionic groups.

The inventors surprisingly found that the presence of an ionomer resin in the blend serves to better homogenise the hydrophilic polymer in the polyolefin and, consequently, to further improve the water retention properties of the resulting composition.

Suitable ionomers include copolymers comprising 5 to 25% by weight of ionic comonomer, such as 10 to 20%. The ionomer resin may have a neutralisation ratio of 10% or more. The ionomer resin may be a random copolymer of poly(ethylene-co-(meth)acrylic) acid. The copolymer may be at least partially neutralised. The copolymer may comprise (meth)acrylic acid comonomer that is acrylic acid comonomer, methacrylic acid comonomer or a combination of acrylic acid and methacrylic acid comonomers. The poly(ethylene-co-(meth)acrylic) acid copolymer may incorporate the (meth)acrylic acid comonomer in an incorporation ratio of 20 mol % or less, such as 15 mol % or less, or 10 mol % or less. The ionomer resin may be a neutralised polyvinyl sulphonic acid. The ionomer resin may be a neutralised sulphonated derivative of a poly(ether ether-keton). Suitable examples of commercial ionomer resins include those available under the trade designation Surlyn™ ionomers, Entira™ ionomers, and Nucrel™ ionomors, each available from The Dow Chemical Company.

When present, the ionomer resin is applied in an amount of 0.1% or more by total weight of the blend, such as 0.2% or more, 0.3% or more, 0.4% or more, or 0.5% or more. When present, the ionomer resin is applied in an amount of 10% or less by total weight of the blend, such as 9% or less, 8% or less, 7% or less, or 6% or less.

The blends as described herein may further comprise one or more additives. The additives may be selected from the group consisting of compatibilisers, flame retardants, colouring agents, processing aids, antioxidants, UV-stabilisers, heat stabilisers, and pigments. In particular, the blend may comprise one or more compatibilisers such that an immiscible blend of polymers become more stable.

The blend may comprise a functionalised polyethylene having one or more hydrophilic groups grafted on a polyethylene as compatibiliser. The functionalised polyethylene may comprise one or more hydrophilic groups selected from the group consisting of anhydride groups, such as acid anhydrides, amine groups, thiamine groups, hydroxyl groups, cyanide groups, carboxylic acid groups, sulphonic acid groups, amide groups, thioamide groups, imide groups, sulphonamide groups, thiol groups, and derivatives thereof. In particular, the functionalised polyethylene may comprises one or more anhydride groups, carboxylic acid groups, hydroxyl groups, and/or derivatives thereof. Preferably, maleic anhydride groups, ethylene acrylic acid groups, such as ethyl methyl acrylate groups, ethylene vinyl alcohol groups, and/or derivatives thereof are selected.

The blends may comprise 1-10% by total weight of the blend of the functionalised polyethylene. In particular, the blend may comprise 1.5-9.5% by total weight of the blend of functionalised polyethylene, such as 2% or more, 2.5% or more, 3% or more, or 3.5% or more, and 9% or less, 8.5% or less, 8% or less, or 7.5% or less. Preferably, the blend comprises 2-8% by total weight of the blend of functionalised polyethylene, and more preferably 3-7%.

By using functionalised polyethylene the hydrophilicity of the filaments and/or the compatibility of polyethylene and hydrophilic polymer may improve. Functionalised polyethylene may stabilise an otherwise immiscible blend of polymers.

The blend and/or the synthetic turf filaments as described herein may further comprise a total amount of additives of 0-25% by total polymer weight. In particular, the amount of additives in the blend may be 0.1% or more by total weight of the blend, such as 1% or more, 3% or more, or 6% or more. The amount of additives in the blend may be 22.5% or less by total weight of the blend, such as 21% or less, 17.5% or less, or 12.5% or less. Preferably, the blend comprises 0.1-20% by total weight of the blend of total additives, and more preferably 0.5-15%. In case the blends comprise one or more flame retardants, the amount of the total flame retardants may be 2.5% or more by total weight of the blend, such as 5% or more, 7.5% or more, 10% or more, or 12.5% or more. Advantageously, the amount of total flame retardants can be relatively low, because the hydrophilic polymer provides some flame retardant properties. Hence, the amount of total flame retardants can be 25% or less by total weight of the blend, such as 22.5% or less, 20% or less, or 17.5% or less.

The synthetic turf filaments preferably have an amount of fillers, such as zeolites, of 5% or less by total weight of the filament, preferably 3% or less, even more preferably, 2% or less, and most preferably 1% or less. High amounts of filler can negatively affect properties such as wear resistance, roughness, resilience and/or stiffness of the synthetic turf filaments.

The artificial turf, comprising polyethylene, comprises synthetic turf filaments. The filaments may have an average Young's modulus, as measured according to ISO 527, in the range of 1-50 cN/tex. In particular, the average Young's modulus of the synthetic turf filaments may be 2-40 cN/tex, such as 6 cN/tex or more, 8 cN/tex or more, 10 cN/tex or more, 12 cN/tex or more, or 15 cN/tex or more, and 36 cN/tex or less, 33 cN/tex or less, 28 cN/tex or less, 25 cN/tex or less, 22 cN/tex or less. Preferably, the average Young's modulus of the synthetic turf filaments is 3-30 cN/tex, more preferably 5-20 cN/tex.

In a preferred embodiment, artificial turf comprising synthetic turf filaments is provided, wherein the filaments comprise a blend, wherein the blend comprises 65-99.5% by total weight of the blend of linear low-density polyethylene, and 0.5-35% by total weight of the blend of polyvinyl alcohol.

In yet a further preferred embodiment, the synthetic turf filaments comprise a blend, wherein the blend comprises 65-95% by total weight of the blend of a polyolefin, 0.5-30% by total weight of the blend of a hydrophilic polymer, and 0.1-10% by total weight of the blend of an ionomer resin, wherein the polyolefin is a polyethylene, a polypropylene, or a combination thereof.

Even more preferred is an artificial turf comprising synthetic turf filaments is provided, wherein the filaments comprise a blend, wherein the blend comprises 65-95% (preferably 60-90%) by total weight of the blend of linear low-density polyethylene, and 0.5-3% (preferably 1-2.5%) by total weight of the blend of polyvinyl alcohol, and 0.1-10% (preferably 0.5-8%) by total weight of the blend of an ionomer resin.

The synthetic turf filaments of the artificial turf, as described herein, advantageously retain water. The filaments comprise a blend, wherein the blend comprises hydrophilic polymer which has the tendency to absorb water. The water can be absorbed from, for example, the air (in the form of rain, fog, etc.), absorbed from water evaporating from the soil, and/or can be supplied by a watering installation. When water is absorbed, the temperature per time moment is lowered. It is believed that the filaments as described herein comprise hydrophilic areas dispersed throughout the filaments. The presence of these hydrophilic areas have at least an advantageous effect on the improved water retention, and possibly also on an even lower temperature per time moment, when compared to known synthetic turf filaments.

In accordance with the invention, the total amount of water required to wet a specific area for a specified time window will be less as compared to a conventional artificial turf. This is important for artificial turf used for playing hockey, in particular at a global level. The invention thus allows as cost reduction in terms of amount of water. Additionally, a reduced amount of water consumption is ecologically friendly.

The invention also provides artificial turf comprising a synthetic backing, wherein the synthetic backing comprises a blend, which blend comprises

-   i) 65-99.5% by total weight of the blend of a polypropylene, and -   ii) 0.5-35% by total weight of the blend of a hydrophilic polymer,     preferably a hydrophilic polymer as described herein, and/or in an     amount as described herein, -   wherein the artificial turf is preferably in the form of a tile or     carpet.

The blend for the synthetic backing comprises 65-99.5% by total weight of the blend of polypropylene. In particular, the blend may comprise 65-95% by total weight of the blend of polypropylene. The amount of polypropylene in the blend may, for instance, be 70% or more by total weight of the blend, such as 75% or more, or 80% or more. The amount of polypropylene in the blend may be 90% or less by total weight of the blend, such as 85% or less. Preferably, the blend comprises 70-85% by total weight of the blend of polypropylene, and more preferably 77.5-82.5%.

The polypropylene may, for example, be selected from the group consisting of polypropylene homopolymer, such as SABIC® PP 500P, or SABIC® PP 506P, polypropylene copolymer, such as polypropylene random copolymer and polypropylene block copolymer, and high melt strength polypropylene. In an embodiment, there is provided an artificial turf comprising the synthetic backing, as described herein, wherein the synthetic backing comprising a polypropylene homopolymer. In particular, the homopolymer can have a melt flow index, as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 230° C., of 1-25 g/10 min, preferably 2-20 g/10 min, more preferably 2-4 g/10 min. Also the homopolymer can have a density, as measured according to ISO 1183, in the range 0.90-0.95 g/cm³.

The synthetic turf filaments as described herein, and/or the synthetic backing as described herein, are in particular suitable for artificial turf, e.g., for landscapes, such as commercial, recreational, and residential landscapes, parks, sports fields, such as sports fields for contact sports, ball sports, and athletics, playgrounds, gardens, and pets.

The invention further provides synthetic backing material comprising a blend as described herein, in particular the blend comprising polypropylene.

Artificial turf comprising the synthetic backing as described herein has improved tuft-lock. It is believed that the presence of hydrophilic polymer within the synthetic filaments and/or synthetic backing advantageously improves the tuft-lock of artificial turf through improved wetting of the (hydrophilic) synthetic filaments, such as the synthetic turf filaments, as described herein by the latex (water emulsion) in the stitch/loop. The hydrophilic character of the filaments improves the ability of the water emulsion to penetrate in between the filaments.

Particularly preferred is an artificial turf wherein the artificial turf filaments and the synthetic backing as described herein are combined. Accordingly, the invention further provides artificial turf, comprising synthetic turf filaments, wherein the synthetic turf filaments comprise a filament blend, which filament blend comprises 65-99.5% by total weight of the filament blend of a polyolefin, 0.5-35% by total weight of the filament blend of a hydrophilic polymer, and optionally an ionomer resin, wherein the polyolefin is a polyethylene, a polypropylene, or a combination thereof, wherein said artificial turf further comprises a synthetic backing, wherein the synthetic backing comprises a backing blend, which backing blend comprises 65-99.5% by total weight of the backing blend of a polypropylene, and 0.5-35% by total weight of the backing blend of a hydrophilic polymer.

The invention further provides synthetic filament comprising a blend as described herein, in particular the blend comprising polyethylene. The synthetic filament may be used in floor covering. The term “floor covering” as used herein is meant to refer to a covering for a floor, i.e., a material applicable on a floor structure. When the floor, or floor structure, is covered with the floor covering, the floor under the floor covering is suitably called a subfloor. The subfloor may be an earthen floor and/or ground floor, in particular a solid ground floor. The synthetic filament can be used in carpets and carpet-like structures. The terms “carpets” and “carpet-like structures” as used herein are meant to refer to substrate layers to which filaments are attached, that have, for example, been attached by mechanically connecting the filaments to the substrate layer. In particular, the synthetic filament is attached to substrate layers predominantly comprising synthetic filaments instead of filaments made of natural material (i.e., synthetic carpets and synthetic carpet-like structures). For example, means of a tufting, weaving, or knitting technique is suitable for connecting the synthetic filament to a substrate layer. The resulting substrate layer may have substantially upright, or upright, synthetic filaments projecting upwardly. The resulting preferably comprises a backing, such as the synthetic backing as described herein.

In an embodiment, there is provided the synthetic filament, as described herein, comprising a blend as described herein, in the form of a synthetic turf filament.

In another embodiment, there is provided the synthetic filament comprising a blend, as described herein, in the form of a synthetic carpet filament. There is further provided a carpet, such as a synthetic carpet, comprising the synthetic filament as described herein, wherein the synthetic filament comprises a blend as described herein. The carpet, or synthetic carpet, may further comprise a backing material comprising a blend, as described herein.

The invention further provides a method of cooling artificial turf, comprising inserting a plurality of a synthetic turf filament as described herein into artificial turf.

There is also provided a use of a synthetic turf filament as defined herein for cooling artificial turf, wherein a plurality of the synthetic turf filament is inserted into artificial turf.

The invention has been described by reference to various embodiments, and methods. The skilled person understands that features of various embodiments and methods can be combined with each other.

All references cited herein are hereby completely incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. For the purpose of the description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term “about”. Also, all ranges include any combination of the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. When referring to a noun (e.g., synthetic turf filament, artificial turf, etc.) in the singular, the plural is meant to be included, or it follows from the context that it should refer to the singular only.

Preferred embodiments of this invention are described herein. Variation of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject-matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

Hereinafter, the invention will be illustrated in more detail, according to specific examples. However, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these example embodiments are provided so that this description will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

EXAMPLES Example 1

Extrusion experiments were performed on a 25 mm twin-screw extruder (L/D40). Different compounds were prepared and extruded into tapes of 15 mm width×1 mm thickness (w×t×∞). A first set of experiments (MY19001 to MY19008) was performed with LLDPE A, a LLDPE type C4 for grass production having a melt flow index as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 190° C. of 2.8 g/10 min, a density as measured according to ISO 1183 of 0.918 g/cm³, and a melting point as measured by DSC of 121° C., and 25 phr of extrudable PVOH (having a T_(g) of 50-60° C.) with different compatibilising agents.

Example 2

Similar experiments as in Example 1 (MY19010 to MY19027) with lower PVOH content are performed, based on LLDPE B, a LLDPE type C4 for grass production having a melt flow index as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 190° C. of 1.0 g/10 min, a density as measured according to ISO 1183 of 0.918 g/cm³, and a melting point as measured by DSC of 121° C.

Example 3

A third set of samples was prepared (MY19028 to MY19039), equal to the set of Example 1, based on LLDPE B. Afterwards, SEM analysis was performed by a FEI Desktop Electron Microscope (see FIGS. 1 and 2). Samples were cross sectioned after cryogenic treatment by liquid nitrogen.

Example 4

Extrusion experiments were performed on a 25 mm twin-screw extruder (L/D40). Different compounds were prepared and extruded into tapes of 15 mm width×1 mm thickness (w×t×∞), then elongated 2.5 times into tapes of 7 mm width×500 μm thickness. A fourth set of experiments (MY19065 to MY19089) was performed with LLDPE C, a LLDPE type C4 for grass production having a melt flow index as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 190° C. of 2.0 g/10 min, a density as measured according to ISO 1183 of 0.918 g/cm³, and a melting point as measured by DSC of 122° C. and 8 phr of extrudable PVOH (having a T_(g) of 50-60° C.) with different ionomers based on a copolymer of ethylene and methylacrylate.

Example 5

Extrusion experiments were performed on a 25 mm twin-screw extruder (L/D40). Different compounds were prepared and extruded into tapes of 15 mm width×1 mm thickness (w×t×∞), then elongated 4.5 times into tapes of 2.5 mm width×200 μm thickness. A fifth set of experiments (MY19093 to MY19117) was performed with LLDPE C and 8 phr of extrudable PVOH (having a T_(g) of 50-60° C.) with different ionomers based on a copolymer of ethylene and methylacrylate.

Cyclic water absorption and release tests were performed on sample specimens of 1.00 m length by mass determination. Water absorption values of maximum 2 wt. % were reported (see FIG. 3).

Example 6

Extrusion experiments were performed on an artificial yarn extrusion production line. A set of experiments (TYR200003 to TYR200005) were performed with compounds similar to the fifth set, based on LLDPE C. These compounds were extruded into artificial grass fibres.

Cyclic water absorption and release tests are performed on sample specimen of 1.00 m length by mass determination. Water absorption values of maximum 4 wt. % were reported (see FIG. 4). 

1. Artificial turf, comprising synthetic turf filaments, the synthetic turf filaments comprise a blend, and the blend comprises 65-99.5% by total weight of the blend of a polyolefin, and 0.5-35% by total weight of the blend of a hydrophilic polymer, wherein the polyolefin is polyethylene, polypropylene, or any combination thereof.
 2. Artificial turf according to claim 1, wherein the blend further comprises an ionomer resin.
 3. Artificial turf according to claim 1, wherein the artificial turf is in the form of a tile or carpet.
 4. Artificial turf according to claim 1, wherein the blend comprises i) 65-95% by total weight of the blend of the polyethylene, and/or ii) 1-30% by total weight of the blend of the hydrophilic polymer, and/or iii) 0.1-10% by total weight of the blend of an ionomer resin.
 5. Artificial turf according to claim 1, wherein the blend further comprises up to 25% by total weight of the blend of one or more additives.
 6. Artificial turf according to claim 1, wherein the polyethylene has i) a density, as measured according to ISO 1183, in the range of 0.88-0.99 g/cm³, and/or ii) a melt flow index, as measured according to ISO 1133 at a load of 2.16 kg and at a temperature of 190° C., of 0.1-10 g/10 min, and/or iii) a melting point, as measured according to ISO 11357, in the range of 100-180° C.
 7. Artificial turf according to claim 1, wherein the polyethylene comprises one or more selected from the group consisting of very low-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium- density polyethylene, and high-density polyethylene.
 8. Artificial turf according to claim 1, wherein the polypropylene is selected from the group consisting of homopolymers of propylene, random copolymers of propylene and one or more other olefins, block copolymers of propylene and one or more other olefins, and terpolymers of propylene, ethylene and dienes.
 9. Artificial turf according to claim 1, wherein the hydrophilic polymer comprises one or more synthetic polymers and/or one or more natural polymers, wherein the one or more synthetic polymers are selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyethylene glycol, polyurethane, N-(2-hydroxypropyl)methacrylamide, xanthane gum, and derivatives thereof, and/or wherein the one or more natural polymers are selected from the group consisting of pectins, chitin, chitosan, dextran, cellulose ethers, starch and derivatives thereof.
 10. Artificial turf according to claim 2, wherein the ionomer resin comprises ionised repeating units, wherein said ionised repeating units comprise one or more ionic groups selected from the group consisting of sulphonate, phosphate, phosphonate, and carboxylate ionic groups.
 11. Artificial turf according to claim 2, wherein the ionomer resin comprises acrylic acid comonomer, methacrylic acid comonomer or a combination of acrylic acid and methacrylic acid comonomers.
 12. Artificial turf according to claim 2, wherein the ionomer resin comprises one or more from the group consisting of a random copolymer of poly(ethylene-co-(meth)acrylic) acid, a polyvinyl sulphonic acid or a sulphonated derivative of a poly(ether ether-ketone), wherein the ionomer resin may be neutralised.
 13. Artificial turf according to claim 1, further comprising a functionalised polyethylene having one or more hydrophilic groups grafted on polyethylene, wherein the one or more hydrophilic groups are selected from the group consisting of anhydride groups, carboxylic acid groups, and hydroxyl groups.
 14. Artificial turf according to claim 13, wherein the functionalised polyethylene is present in the blend in an amount of 1-10% by total weight of the blend.
 15. Artificial turf according to claim 5, wherein the additives comprise one or more selected from the group consisting of compatibilisers, flame retardants, colouring agents, heat stabilisers, processing aids, antioxidants, UV-stabilisers, and pigments.
 16. Artificial turf according to claim 1, wherein the synthetic turf filaments have a Young's modulus, as measured according to ISO 527, in the range of 1-50 cN/tex.
 17. Artificial turf according to claim 1, wherein the blend comprises 65-99.5% by total weight of the blend of linear low-density polyethylene, and 0.5-35% by total weight of the blend of polyvinyl alcohol.
 18. Artificial turf according to claim 1, wherein the synthetic turf filaments comprise 5% or less by total weight of the synthetic turf filaments of filler.
 19. Artificial turf, comprising a synthetic backing, the synthetic backing comprises a blend, the blend comprises i) 65-99.5% by total weight of the blend of a polypropylene, and ii) 0.5-35% by total weight of the blend of a hydrophilic polymer, preferably the a hydrophilic polymer as defined in claim
 9. 20. Artificial turf according to claim 19, wherein the artificial turf is in the form of a tile or carpet.
 21. Artificial turf comprising synthetic turf filaments as defined in claim 1, and comprising a synthetic backing, the synthetic backing comprises a blend, the blend comprises i) 65-99.5% by total weight of the blend of a polypropylene, and ii) 0.5-35% by total weight of the blend of a hydrophilic polymer, preferably the hydrophilic polymer comprises one or more synthetic polymers and/or one or more natural polymers, wherein the one or more synthetic polymers are selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyethylene glycol, polyurethane, N-(2-hydroxypropyl)methacrylamide, xanthan gum, and derivatives thereof, and/or wherein the one or more natural polymers are selected from the group consisting of pectins, chitin, chitosan, dextran, cellulose ethers, such as hydroxypropylcellulose, starch and derivatives thereof.
 22. Synthetic backing material, comprising a blend as defined in claim
 19. 23. Synthetic filament, comprising a blend as defined in claim
 1. 24. Method of cooling artificial turf, comprising inserting a plurality of synthetic turf filaments as defined in claim 1 into artificial turf. 